A ubiquitin E2 variant protein acts in axon termination and synaptogenesis in Caenorhabditis elegans

Genetics. 2010 Sep;186(1):135-45. doi: 10.1534/genetics.110.117341. Epub 2010 Jun 30.


In the developing nervous system, cohorts of events regulate the precise patterning of axons and formation of synapses between presynaptic neurons and their targets. The conserved PHR proteins play important roles in many aspects of axon and synapse development from C. elegans to mammals. The PHR proteins act as E3 ubiquitin ligases for the dual-leucine-zipper-bearing MAP kinase kinase kinase (DLK MAPKKK) to regulate the signal transduction cascade. In C. elegans, loss-of-function of the PHR protein RPM-1 (Regulator of Presynaptic Morphology-1) results in fewer synapses, disorganized presynaptic architecture, and axon overextension. Inactivation of the DLK-1 pathway suppresses these defects. By characterizing additional genetic suppressors of rpm-1, we present here a new member of the DLK-1 pathway, UEV-3, an E2 ubiquitin-conjugating enzyme variant. We show that uev-3 acts cell autonomously in neurons, despite its ubiquitous expression. Our genetic epistasis analysis supports a conclusion that uev-3 acts downstream of the MAPKK mkk-4 and upstream of the MAPKAPK mak-2. UEV-3 can interact with the p38 MAPK PMK-3. We postulate that UEV-3 may provide additional specificity in the DLK-1 pathway by contributing to activation of PMK-3 or limiting the substrates accessible to PMK-3.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Caenorhabditis elegans / cytology*
  • Caenorhabditis elegans / enzymology*
  • Caenorhabditis elegans / metabolism
  • Caenorhabditis elegans Proteins / metabolism
  • Guanine Nucleotide Exchange Factors / metabolism
  • MAP Kinase Kinase Kinases / metabolism
  • MAP Kinase Signaling System
  • Mitogen-Activated Protein Kinase Kinases / metabolism
  • Mitogen-Activated Protein Kinases / metabolism
  • Molecular Sequence Data
  • Motor Neurons / cytology
  • Motor Neurons / metabolism
  • Presynaptic Terminals / enzymology
  • Presynaptic Terminals / metabolism*
  • Substrate Specificity
  • Ubiquitin-Conjugating Enzymes / chemistry
  • Ubiquitin-Conjugating Enzymes / metabolism*


  • Caenorhabditis elegans Proteins
  • Guanine Nucleotide Exchange Factors
  • RPM-1 protein, C elegans
  • Ubiquitin-Conjugating Enzymes
  • Mitogen-Activated Protein Kinases
  • pmk-3 protein, C elegans
  • DLK-1 protein, C elegans
  • MAP Kinase Kinase Kinases
  • Mitogen-Activated Protein Kinase Kinases